Late‐Stage Heteroarylation of Hetero(aryl)sulfonium Salts Activated by α‐Amino Alkyl Radicals

Palladium-Catalyzed Carbonylative Sonogashira Coupling of Aryl Thianthrenium Salts with Arylalkynes

Alkynones are valuable compounds with applications in various areas. In this work, we developed an efficient carbonylation procedure for the carbonylative cross-coupling of aryl thianthrenium salts with aromatic alkynes. Various useful alkynones were produced in moderate to excellent yields under mild conditions. Notably, among the various tolerated functional groups, the bromide group can be maintained, which is ready for further coupling reactions.

Hydrodeuteroalkylation of Unactivated Olefins Using Thianthrenium Salts

Isotopically labeled alkanes play a crucial role in organic and pharmaceutical chemistry. While some deuterated methylating agents are readily available, the limited accessibility of other deuteroalkyl reagents has hindered the synthesis of corresponding products. In this study, we introduce a nickel-catalyzed system that facilitates the synthesis of various deuterium-labeled alkanes through the hydrodeuteroalkylation of d2-labeled alkyl TT salts with unactivated alkenes. Diverging from traditional deuterated alkyl reagents, alkyl thianthrenium (TT) salts can effectively and selectively introduce deuterium at α position of alkyl chains using D2O as the deuterium source via a single-step pH-dependent hydrogen isotope exchange (HIE). Our method allows for high deuterium incorporation, and offers precise control over the site of deuterium insertion within an alkyl chain. This technique proves to be invaluable for the synthesis of various deuterium-labeled compounds, especially those of pharmaceutical relevance.

Late-stage C-H Functionalization of Tryptophan-Containing Peptides with Thianthrenium Salts: Conjugation and Ligation

Bioorthogonal late-stage diversification of structurally complex peptides bears enormous potential for drug discovery and molecular imaging, among other applications. Herein, we report on a palladium-catalyzed C-H arylation of tryptophan-containing peptides with readily accessible and modular arylthianthrenium salts. Under exceedingly mild reaction conditions, the late-stage diversification of structurally complex peptides was accomplished. The tunability and ease of preparation of arylthianthrenium salts allowed the expedient stitching of tryptophan-containing peptides with drug, natural product, and peptidic scaffolds by forging sterically congested biaryl linkages. The robustness of the palladium catalysis regime was reflected by the full tolerance of a plethora of sensitive and coordinating functional groups. Hence, our manifold enabled efficient access to highly decorated, labelled, conjugated, and ligated linear and cyclic peptides.

Meerwein-type Bromoarylation with Arylthianthrenium Salts

Herein, we report a photocatalyzed Meerwein-type bromoarylation of alkenes with stable arylthianthrenium salts, formed by site-selective C-H thianthrenation. This protocol can be applied to late-stage functionalization of a variety of biomolecules that are difficult to access by other aryl coupling reagents. Halogen introduction allows for a variety of follow-up transformations, affording numerous biologically active skeletons.

C(sp3)-H/C(sp3)-H Dehydrogenative Radical Coupling of Glycine Derivatives

Here we report a general C(sp³)-H/C(sp³)-H dehydrogenative coupling strategy for the preparation of various natural or unnatural amino acids from readily available glycine derivatives and hydrocarbons through a combination of SET and HAT process.

Sustainable Thioetherification via Electron Donor-Acceptor Photoactivation Using Thianthrenium Salts

The synthesis of sulfides has been widely studied because this functional subunit is prevalent in biomolecules and pharmaceuticals, as well as being a useful synthetic platform for further elaboration. Thus, various methods to build C-S bonds have been developed, but typically they require the use of precious metals or harsh conditions. Electron donor-acceptor (EDA) complex photoactivation strategies have emerged as versatile and sustainable ways to achieve C-S bond formation, avoiding challenges associated with previous methods. This work describes an open-to-air, photoinduced, site-selective C-H thioetherification from readily available reagents via EDA complex formation that tolerates a wide range of different functional groups. Moreover, C(sp² )-halogen bonds remain intact using this protocol, allowing late-stage installation of the sulfide motif in various bioactive scaffolds, while allowing yet further modification through more traditional C-X bond cleavage protocols. Additionally, various mechanistic investigations support the envisioned EDA complex scenario.

Trifluoromethyl Thianthrenium Triflate: A Readily Available Trifluoromethylating Reagent with Formal CF3+, CF3•, and CF3- Reactivity

Here we report the synthesis and application of trifluoromethyl thianthrenium triflate (TT-CF₃⁺OTf^–) as a novel trifluoromethylating reagent, which is conveniently accessible in a single step from thianthrene and triflic anhydride. We demonstrate the use of TT-CF₃⁺OTf^– in electrophilic, radical, and nucleophilic trifluoromethylation reactions.